Kevork Djansezian/Getty Image(LOS ANGELES) -- The dragnet for Christopher Dorner has gone international as police raided a Mexican hotel overnight and are looking into surveillance footage of the accused cop killer purchasing SCUBA gear at a California sporting goods store.

Dorner is seen in the footage, reportedly from the Sports Chalet in Torrance, Calif., on Feb. 1, purchasing and refilling air tanks days before his string of alleged killings began. The 33-year-old fugitive former LAPD cop was assigned to a naval undersea warfare unit while serving in the Navy.

"There's no telling why he was purchasing SCUBA gear," Lt. Andy Neiman said at a press conference Tuesday morning.

A hotel in Tijuana, Mexico, was raided Monday night on a tip that Dorner was there, but Dorner was not found.

On Monday, Border Patrol officials said there were longer than usual lines at the San Diego-Tijuana border crossing because of more intense scrutiny of cars and pedestrians heading south. The Border Patrol said the closer inspections were part of the manhunt for Dorner.

In an affidavit, the U.S. Marshals Service mentioned a possible associate of Dorner's, whose family member had property in Arrowbear Lake, Calif., KABC reported. The affidavit identifies the associate only as "JY."

The property at Arrowbear Lake is close by Big Bear Mountain that has been the scene of a huge manhunt since Dorner's burned out truck was found there last Thursday.

Sources tell ABC News that police are also trying to reconstruct the last six months of Dorner's life in the hopes that it will lead them to the suspect.

In retracing Dorner's life, police will be helped -- as well as hampered -- by the hundreds of tips pouring in to police claiming sightings of Dormer.

Dorner faces capital murder charges that involve the killing of Riverside police officer Michael Crain, who was gunned down in an ambush last Thursday. A capital murder charge could result in the death penalty if convicted.

The charges do not involve the slayings of Monica Quan and her fiancé, who were found shot to death Feb. 3. Quan was the daughter of former LAPD captain Randal Quan, who was mentioned as a target of Dorner's fury in his manifesto.

Dorner released the 6,000 word so-called "manifesto" on his Facebook page which outlined his anger at the Los Angeles Police Department for firing him, and made threats against individuals he believed were responsible for ending his career with the police force five years ago. The LAPD has assigned 50 protection details to guard officers and their families who were deemed possible targets.